Effects Of Vehicle Vibration On Brain Functional Connectivity Based On Near-infrared Spectroscopy In Drivers

It is well documented from several countries that professional drivers have an increased risk of stroke. The risk of stroke is higher among drivers carrying passengers than among drivers carrying goods. We also found an increased relative risk ratio for stable city bus drivers compared to other drivers. There are several disadvantages during driving such as working long hours, focusing on driving, overworking pressure and pressed spirit. The environment of drivers also surrounded with high temperature, noise, vibration. These reasons would lead to the professional drivers suffer from stroke.The purpose of this paper is to assess the effects of vehicle vibration on brain functional connectivity of professional drivers using coherence analysis of changes in cerebral tissue oxyhaemoglobin concentrations (△HbO2) signals. The signals were obtained by near-infrared spectroscopy (NIRS). This paper indicates the driver’s brain functional connectivity as a new index which could avoid traffic accidents caused by the vehicle vibration leading to driver’s stroke.The NIRS signals obtained at cortical regions mainly reflect regional spontaneous hemodynamic oscillations that originate from spontaneous cortical activity. The power spectra of △HbO2 signals exhibit oscillations in various frequency bands. Different characteristic frequencies of △HbO2 signals, which indicate possible regulatory mechanisms of the tissue oxygenation signal, have been identified using wavelet analysis. The characteristic frequencies are divided into six interval:Ⅰ,0.6-2 Hz、Ⅱ,0.145-0.6 Hz、Ⅲ,0.052-0.145 Hz、Ⅳ,0.021-0.052 Hz、Ⅴ,0.0095-0.021 Hz、 Ⅵ,0.005-0.0095 Hz. Data for the NIRS signals were obtained simultaneously from the left and right prefrontal cortex (PFC). The PFC plays an important role in planning complex cognitive behaviors, personality expression and decision-making. Therefore, we can assess the brain functional connectivity in various frequency intervals using wavelet coherence and phase coherence analysis in professional drivers.Continuous recordings of NIRS signals were obtained from the left and right prefrontal lobes in 13 subjects with cerebral infarction (CI) and 21 healthy elderly subjects during the resting state. The brain functional connectivity was analyzed using wavelet-based coherence analysis. The brain functional connectivity was significantly lower in interval Ⅲ in elderly with CI than in healthy subjects. Clinical studies demonstrated that resting-state connectivity is altered in disorders such as stroke. A system was designed for assessing brain functional connectivity based on partial least squares. This system could be used for detecting stroke in early time and assessing the effectiveness of functional recovery following a CI.The effects of vehicle vibration on driver’s brain functional connectivity were analyzed. A vibration system with driver’s seat was established to simulate the vehicle vibration. A total of 11 subjects were exposed to the vibration at frequencies 3,4.5,6 Hz and resting state for 20 min in a randomized order on 4 separate days. The brain functional connectivity in interval Ⅱ and Ⅲ were significantly lower at vibration than at resting state. The brain functional connectivity was lowest at 4.5 Hz. However, no significant differences in brain functional connectivity were found among the vibration at 3,4.5 and 6 Hz.In conclusion, our results show that vibration induces lower brain functional connectivity and this reflects a decreased synchronization which may increase the risk of stroke. The driver’s brain functional connectivity was suggested to be a parameter in the manufacture of vehicle. It could avoid the professional driver suffering from stroke by transform the frequency of vibration. The traffic accidents which caused by driver’s sudden stroke will be decreased.